Left-behind children Child 1 China 1 Cross-Sectional Studies 1 Cross-sectional studies 1 Dental Caries 1 Dental caries 1 Emigrants and Immigrants 1 Externalizing behavior problems 1 Female 1 Hui ethnicity 1 Humans 1 Male 1 Oral Health 1 Oral Hygiene 1 Oral health related behaviors 1 Parental migration 1 Parents 1 Risk Factors 1 Rural China 1 Rural Population 1 School-aged children 1 Surveys and Questionnaires 1 child 1 child parent relation 1 cross-sectional study 1 dental caries 1 female 1 health 1 human 1